The main focus of this proposal is the chemistry of the proton (H+), in acids and hydrogen bonding. Metalloporphyrins are an additional interest. The broad objective is to uncover fundamental new chemistry that provides a basis for the molecular level understanding of protons and hemoproteins in chemical and biological systems. A knowledge base of fundamental chemistry is important to the molecular underpinnings of the modern medicine. Specific aims include (i) the characterization of successive hydrates of the proton (H5O2+, H7O3+, H9O4+ etc. up to Haq+) and understanding their distinctive and peculiar IR spectral properties (ii) the measurement of acid strength outside presently accessible ranges so that the newly recognized phenomenon of basicity suppression can be quantified, (iii) the development of an infrared ?NH basicity scale for ? bases (arenes, alkenes, alkynes), (iv) the exploration of new bifurcated H-bonds, (v) the activation of alkanes with carborane acids, and (vi) the exploitation of strong, carborane-based electrophiles to isolate novel dications. In porphyrin research, specific aims include (i) questioning the long-accepted concept of quantum mechanically admixed S = 3/2,5/2 spin states in iron(III) porphyrins and (ii) investigating whether there is a relationship between field strength in the Magnetochemical Series and the binding strength of axial ligands in iron(III) porphyrins. The research plan exploits the special properties of carborane anions as weakly coordinating anions and as superweak conjugate bases of carborane acids. Emphasis in these studies is placed on the definitive characterization of pure materials by X-ray crystallography and a variety of spectroscopic methods, particularly NMR and IR spectroscopies. PUBLIC HEALTH RELEVANCE: The study of the proton is central to fundamental chemistry which, in turn, is the hidden engine of modern biomedical science. Fundamental chemistry gives foundation to the molecular level understanding of disease control and thus, is critical to public health. As well as expanding the knowledge base, NIH-funded fundamental chemistry is a critically important and exceptionally fertile ground for training the next generation of scientists in problem solving in the chemically-based sciences, encouraging the best of them to pursue careers in chemistry and biomedical science.